1. Field of the Invention
This invention relates to a polymer composition and a core-shell elastomer used therefor. More specifically, the invention relates to a composition which comprises a cyclic structure-containing polymer and a core-shell elastomer which contains in a shell component a specific acrylate or methacrylate monomer as a constituent.
2. Prior Art
Heretofore, it has been well known that cyclic olefin random copolymers obtained by copolymerizing ethylene with a cyclic olefin such as tetracyclododecene or norbornene are synthetic resins which are excellent in transparency, whose heat resistance, heat aging resistance, chemical resistance, solvent resistance, dielectric properties and rigidity are well balanced, and which exhibit excellent performance in the field of optical materials such as optical memory disks and optical fibers. These copolymers have been proposed in JP-A-60-168708 (the term "JP-A" as used herein means an "unexamined published Japanese patent application), JP-A-61-98780, JP-A-61-115912, JP-A-61-115916, JP-A-61-120816 and JP-A-62-252407. It is also known that the cyclic olefin random copolymers disclosed in these prior arts exhibit excellent performance in the field of structural materials.
However, although these cyclic olefin copolymers are superior in heat resistance and rigidity, they have room for improvement of their impact resistance. It is desired that impact resistance be improved while transparency of these cyclic olefin copolymers is retained.
JP-A-1-163241 proposes a composition comprising a cyclic olefin random copolymer having a specific softening temperature (TMA) and a specific .alpha.-olefin elastic copolymer as a resin whose impact resistance is improved without impairing excellent properties such as heat resistance, heat aging resistance and chemical resistance.
Further, a composition comprising a cyclic olefin copolymer which is composed of a product obtained by reacting a specific cyclic olefin random copolymer with a specific soft copolymer in the presence of an organic peroxide has been proposed in JP-A-2-167318 as a cyclic olefin copolymer composition having improved impact resistance.
However, the compositions comprising cyclic olefin copolymers as proposed in JP-A-1-163241 and JP-A-2-167318 have improved impact resistance, but their transparency is insufficient and hence, there is room for improvement.